The flow required to lubricate the packing and cylinders is quite small, and the pressure necessary to inject the lubricant at these locations is quite high. Therefore, small plunger pump (force-feed lubricators) systerns are used. The force-feed lubricators are usually driven by the compressor crankshaft.
The two basic types of cylinder lubrication systems are the pump-topoint system and the divider-block system. The pump-to-point system provides each lubrication point with its own lubricator pump. Thus, if the compressor cylinders and packing require six lubrication points, the lubricator box would be supplied with six cam driven pumps. The dividerblock system uses one or more lubricator pumps to supply a divider block, which then distributes the flow to each of the lubrication points. The two systems are sometimes combined such that each stage of compression is provided with its own pump and a divider block to distribute the flow between the cylinders and packing of that particular stage.
Oil is supplied to this system from the frame lube oil system or from an overhead tank. This oil comes in contact with and thus contaminates the gas being compressed. Gas/oil compatibility should be checked.